Direct Observation of Ordered Configurations of Hydrogen Adatoms on Graphene

Abstract

Ordered configurations of hydrogen adatoms on graphene have long been proposed, calculated and searched for. Here we report direct observation of several ordered configurations of H adatoms on graphene by scanning tunneling microscopy. On the top side of the graphene plane, H atoms in the configurations appear to stick to carbon atoms in the same sublattice. A gap larger than 0.6 eV in the local density of states of the configurations was revealed by scanning tunneling spectroscopy measurements. These findings can be well explained by density functional theory calculations based on double sided H configurations. In addition, factors that may influence H ordering are discussed.

A simple method to tune graphene growth between monolayer and bilayer

“…It is known that hydrogen can significantly affect graphene's growth and properties. 13,15,35,36 However, since the H 2 flow conditions were kept the same after the carbon source (CH 4 ) was introduced, it should be something else that caused the difference between monolayer and bilayer growth. Due to unavoidable outgasing in the furnace at elevated temperatures and air leak during the APCVD process, oxygen exists in the furnace especially when H 2 flow is not on.…”

Probing Bilayer Grain Boundaries in Large‐Area Graphene with Tip‐Enhanced Raman Spectroscopy

“…[28] In the nucleation process of CVD graphene, sp 3 type defects associated with the H 2 precursor are expected to be formed. [25,26] Recently, sp 3 defects were experimentally observed by STM [29] and Raman spectroscopy, [30] for artificially treated graphene samples. From the D′ peak, our results show the first TERS imaging of hydrogen-bonded sp 3 defects at the NS of unmodified graphene (Figure 5f).…”

Theoretical study of the dynamics of atomic hydrogen adsorbed on graphene multilayers

“…Hydrogenation of graphene, for instance, was found, both theoretically and experimentally, to be an effective way to turn this system from a gapless semiconductor into a gapful one with a tunable band gap [1][2][3][4][5][6]. Controlled hydrogenation, on the other hand, has been predicted to induce interesting magnetic states with potential applications in spintronics [7][8][9][10][11][12].…”